Renal 6 Flashcards
reasons for AVP secretion
increased osmolarity, decreased blood volume, decreased blood pressure
what are the two components of the renal countercurrent exchange system
countercurrent multiplier
countercurrent exchanger
what is the countercurrent multiplier
the loop of henle
what is the countercurrent exchanger
the peritubular capillaries (vasa recta)
what is responsible for high osmolarity deep in medulla
nephrons and vasa recta of juxtamedullary nephrons that extend deep into medulla
What happens to filtrate as it enters descending limb
Becomes progressively more concentrated as it loses water to the increasingly hypertonic interstitium
- no solutes transported
What happens to filtrate as it grows up ascending limb
Pumps out Na, K, Cl so becomes hyposmotic
- no aquaporin channels
Where does majority of reabsorption take place
Proximal tubule, 75%
Where does 25% of reabsorption take place
Na and K reabsorption occurs in ascending limb of loop of henle
What transporter are on apical surface of ascending limb
Na-K-Cl cotransporter
What tranporters are on basolateral membrane of ascending loop
Na-K ATPase
K-Cl cotransporter
K and Cl leak channels
Where does NKCC transporter on apical membrane of ascending loop use energy from
Energy stored in Na concentration gradient to move Na, K and 2 Cl into epithelial cells
What is target of loop diuretic drugs for treatment of hypertension and edema
NKCC
Prevents ions from entering and less H20 reabsorption
Why doesnt water entering interstitum via descending limb dilute the hyperosmotic medulla
Opposite direction loop of vasa recta picks some solute up and loses some water as it travels by ascending limb creating hyperosmotic blood
Thus creating gradient allowing water from descending to move into vasa recta
What is the main job of multiplier
Create hypertonic interstitium
